Hydraulic failure in tilt under load

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travski

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May 29, 2015
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Hi Everyone, I own a Bobcat s205 high flow 09 model it has a 4 in one bucket. I'm having a problem with the tilt hydraulics on the machine.If I go into a pile of gravel or whatever and get a decent load and lift and tilt while going back, the tilt fuction on the bobcat fails.The bucket creeps down, I can tilt up and it will hold but as soon as I stop it goes down. It only happens every other time. I won't get it for a while and then heaps. It seems worse when the oils have warmed up. The rams have recently been serviced. I've had it in at bobcat and they can't find the problem. They replaced all the seals and could not find the problem. It was good this morning for about halve an hour and it started doing it again. Very frustrating.Any help would be much appreciated.
 

Tazza

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It could be bad load checks, it could also be that the aux hydraulics are some how working, dirverting oil flow away from the lift/tilt circuit. Generally if it was the aux hydraulics, it would be doing it all the time though.
You have started in the right place, the cylinder seals.
 

7LBSSMALLIE

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It could be bad load checks, it could also be that the aux hydraulics are some how working, dirverting oil flow away from the lift/tilt circuit. Generally if it was the aux hydraulics, it would be doing it all the time though.
You have started in the right place, the cylinder seals.
inspect the bics lockout valve for blown seals or plugged screen
 
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travski

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It could be bad load checks, it could also be that the aux hydraulics are some how working, dirverting oil flow away from the lift/tilt circuit. Generally if it was the aux hydraulics, it would be doing it all the time though.
You have started in the right place, the cylinder seals.
Thanks for your reply.It happens occasionally and sometimes I can cancel the failure by lifting quickly or opening the bucket.it can happen when I'm going into a pile with a full bucket or when I come over a pile with the bucket open and close the 4 in 1. Could bad load checks cause this occasionally? would bobcat check this? I've had it in at bobcat trying to find the problem, they could not find the problem.they said they checked and replaced all the seals. We have now got it at the hydraulic place checking there service on the affected hyd cyl.I'm now thinking its the hydraulic cylinders that are failing but why is it only doing it occasionally? Could it be the rams that are poorly serviced?
 

Tazza

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Thanks for your reply.It happens occasionally and sometimes I can cancel the failure by lifting quickly or opening the bucket.it can happen when I'm going into a pile with a full bucket or when I come over a pile with the bucket open and close the 4 in 1. Could bad load checks cause this occasionally? would bobcat check this? I've had it in at bobcat trying to find the problem, they could not find the problem.they said they checked and replaced all the seals. We have now got it at the hydraulic place checking there service on the affected hyd cyl.I'm now thinking its the hydraulic cylinders that are failing but why is it only doing it occasionally? Could it be the rams that are poorly serviced?
I guess it is possible the cylinders are to blame, but i don't know if it's possible for them to work and not work. When the seal goes, it's gone.
Load checks are a possibility, if they aren't seating correctly.
 

jerry

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I guess it is possible the cylinders are to blame, but i don't know if it's possible for them to work and not work. When the seal goes, it's gone.
Load checks are a possibility, if they aren't seating correctly.
were the cyl seals shot when they did the service? If they were in pieces could be small bits floating in the system causing trouble.
 

farmshop

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were the cyl seals shot when they did the service? If they were in pieces could be small bits floating in the system causing trouble.
possibly they missed a scored barrel. Hyd problems can be magnified when the oil is warm. Try lifting the seat bar when it is creeping down. If it stops it is in the spool valve. if not could be cylinder or lock valve. You can try dead heading the cylinder with pressure to see if one gets hot that one is the bad one cause it only gets hot because oil is flowing through
 
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travski

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were the cyl seals shot when they did the service? If they were in pieces could be small bits floating in the system causing trouble.
I got it back from the hydraulic shop and the rams are fine..Yes, The cyl seals were shot, one was real bad and the other was about to go.We had a crucial job to finish and I had to keep working it. pieces could be in the system.Whats the best way to flush the hyd system?
 

jerry

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I got it back from the hydraulic shop and the rams are fine..Yes, The cyl seals were shot, one was real bad and the other was about to go.We had a crucial job to finish and I had to keep working it. pieces could be in the system.Whats the best way to flush the hyd system?
It would seem that seal parts would get filtered out but a 853 here had the tilt cyl seal break up and then we had trouble with the aux solenoids sticking. May or may not be related. Hook a hose up and run a couple gallons out of the couplers to see if anything comes out. You can always strain it and reuse it.
 
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travski

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It would seem that seal parts would get filtered out but a 853 here had the tilt cyl seal break up and then we had trouble with the aux solenoids sticking. May or may not be related. Hook a hose up and run a couple gallons out of the couplers to see if anything comes out. You can always strain it and reuse it.
The hydraulic failure still happens when I lift the lap bar. I'm going to give the hyd system a complete flush and see how that goes. If it still fails then I will look at the lock valve.Would bobcat do a complete hydr flush when taken in for a 1000 hr service?This machine has done 2700hrs and I'm not sure if it has ever had this done.
 

rnbuck01

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The hydraulic failure still happens when I lift the lap bar. I'm going to give the hyd system a complete flush and see how that goes. If it still fails then I will look at the lock valve.Would bobcat do a complete hydr flush when taken in for a 1000 hr service?This machine has done 2700hrs and I'm not sure if it has ever had this done.
Before you do anything, pressure test both cylinders. Then work your way to the control valve.
 
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travski

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Before you do anything, pressure test both cylinders. Then work your way to the control valve.
Pressure tested the hyd cyl and they are fine. drained the hyd sys and put new oil in it. it still did it. Our mechanic replaced the hoses from the ram to the control box and now he's got it stuck in float. don't know how he did this. Now we have to remove the spool valve to reset it supposedly. This is what bobcat said. Is there a stop valve on the control valve or is it built in? Do you think the control valve needs to be serviced or replaced? It blows my mind that bobcat can't explain it or fix it. I'm in Australia which doesn't help. It's got to be the control valve.......
 

Tazza

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Pressure tested the hyd cyl and they are fine. drained the hyd sys and put new oil in it. it still did it. Our mechanic replaced the hoses from the ram to the control box and now he's got it stuck in float. don't know how he did this. Now we have to remove the spool valve to reset it supposedly. This is what bobcat said. Is there a stop valve on the control valve or is it built in? Do you think the control valve needs to be serviced or replaced? It blows my mind that bobcat can't explain it or fix it. I'm in Australia which doesn't help. It's got to be the control valve.......
You should just need to move the pedal the opposite direction to pop it out of detent mode.
 
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travski

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You should just need to move the pedal the opposite direction to pop it out of detent mode.
Farmshop you might be on the money. I had the top bobcat mechanic come out and he freed the float by freeing the bar that goes to the spool valve. the balls that activate it are corroded. Won't be using float again, major work to fix it properly. I got it to fail while he was there and tilted up while it was failing. he got a heat gun and tested both, the right one was way hotter than the left. He reckons it is bypassing through the piston, and that the piston might not be seated or done up tight enough. I took it off and took it down to the hydro shop for them to redo it. Should get it back tomorrow. Hopefully this will fix the problem. He has seen this type of thing before on a new machine. the piston isn't correctly tightened. I guess the only way to truly test a cylinder is under work conditions, they couldn't find it at their workshop.
 
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travski

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Farmshop you might be on the money. I had the top bobcat mechanic come out and he freed the float by freeing the bar that goes to the spool valve. the balls that activate it are corroded. Won't be using float again, major work to fix it properly. I got it to fail while he was there and tilted up while it was failing. he got a heat gun and tested both, the right one was way hotter than the left. He reckons it is bypassing through the piston, and that the piston might not be seated or done up tight enough. I took it off and took it down to the hydro shop for them to redo it. Should get it back tomorrow. Hopefully this will fix the problem. He has seen this type of thing before on a new machine. the piston isn't correctly tightened. I guess the only way to truly test a cylinder is under work conditions, they couldn't find it at their workshop.
It seems like it isn't the hydraulic cylinders. They were tested again and redone. It is now at bobcat and they are going through it. I'll let you all know when they find the problem. Thanks.
 
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travski

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It seems like it isn't the hydraulic cylinders. They were tested again and redone. It is now at bobcat and they are going through it. I'll let you all know when they find the problem. Thanks.
Just an update. The machine has been in at bobcat for a month now and they still haven't fixed it.Lucky they gave us a brand new S590 to use till it's fixed.I hope they never fix it........
 

Tazza

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Just an update. The machine has been in at bobcat for a month now and they still haven't fixed it.Lucky they gave us a brand new S590 to use till it's fixed.I hope they never fix it........
Wow, he dealer can't even sort it out, what chance did we have with working it out?
Shame they won't just do a swap over for you )
 
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travski

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Wow, he dealer can't even sort it out, what chance did we have with working it out?
Shame they won't just do a swap over for you )
Yeah,that's what all the workers are saying.Trade in. Supposedly they have replaced the spool valve and it still does it.
 

farmshop

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Yeah,that's what all the workers are saying.Trade in. Supposedly they have replaced the spool valve and it still does it.
We had a s175 that would drop when you tried to lift went through cylinders seals etc. Ended up being a crack in the spool valve. Dealer had a used valve for 1500 which is way better than 3500 for a new one
 

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